Degradation of Azo Dye Acid Orange 7 by UV-Activated Common Peroxides in Seawater System

Seawater substitution is one of the effective routes to alleviate the shortage of water resources, and its high saline matter can be used in printing and dyeing industry. However, the treatment of the formed dyeing wastewater is difficult for the high salt. This paper using ultraviolet (UV) light to activate persulfate (PS), hydrogen peroxide (H₂O₂), Oxone (PMS) to degrade azo dye Acid orange 7 (AO7) in seawater. Based on the results, AO7 was effectively degraded by the three peroxides under 254 nm UV activation, and even the benzene and naphthalene rings of AO7 were decomposed thoroughly. With the increasing peroxide dosage, AO7 degradation rate increases, and the common anions in seawater (SO₄^2-, HCO₃^-, Cl^-) have little effects on its destruction. The quenching results show that Cl₂^-· is expected to be the major species responsible for AO7 degradation in seawater system.